1. Field of the Invention
The present invention relates to an elongated sanitary napkin having a vagina-facing region and an intergluteal cleft-facing region elongated rearward thereof and more particularly to a sanitary napkin which can be kept in close contact with the intergluteal cleft, which extends posteriorly from the anus of the body, and can also follow the deformation of the intergluteal cleft so as to be effective in preventing rearward leakage of menstrual blood during sleep.
2. Description of the Related Art
Conventional sanitary napkins include ones having a protruding structure, which is intended to come into close contact with the wearer's body, on a skin-side surface of a napkin body containing a liquid absorbent layer.
Patent Publication 1 identified below discloses a sanitary napkin including a primary absorbent member of a triangular cross-section. This primary absorbent member is composed of an absorbent core for absorption and retention of liquid and an outer cover covering the absorbent core. In this sanitary napkin disclosed in Patent Publication 1, the primary absorbent member comes into close contact with the vaginal opening so that menstrual blood can be mainly absorbed and retained by the primary absorbent member. The sanitary napkin also includes a secondary absorbent member which is flat and intended to come into contact with garments and the primary absorbent member is disposed on the secondary absorbent member.
Patent Publication 2 discloses a sanitary napkin including a tube of absorbent material having a function of absorbing liquid. This tube of absorbent material is composed of an absorbent material shaped into a tube and a cover covering the absorbent material and therefore the tube of absorbent material is allowed to comfortably fit to the vaginal opening of a wearer. Here, the tube of absorbent material is disposed on a base pad.
Patent Publication 3 identified below discloses a hump of a triangular cross-section bulging from a skin-side surface of a sanitary napkin. This hump is composed of an absorbent body and a stiffening element disposed between a liquid-permeable topsheet and a liquid absorbent layer, and the stiffening element is formed of a rigid material such as a plastic sheet. In the sanitary napkin disclosed in Patent Publication 3, even when the hump reinforced by the stiffening element comes into contact with the vaginal opening and is subjected to a compressive force due to body pressure, the hump can keep the sanitary napkin in close contact with the vaginal opening without being crushed down.
Patent Publication 3 also discloses in FIG. 5 an embodiment in which the stiffening element formed of a plastic sheet has a raised portion at its rear end and describes that the raised portion can fit in the intergluteal cleft.
Patent Publication 4 identified below discloses a sanitary napkin having a heaped protrusion in a rear region of a skin-side surface. From the description of Patent Publication 4, it is unclear how the protrusion is constituted, but it describes that the protrusion comes into contact with the cleft of the buttocks to prevent rearward leakage of menstrual blood.    Patent Publication 1: Japanese Unexamined Patent Publication No. H11-500940    Patent Publication 2: Japanese Unexamined Patent Publication No. 2002-512851    Patent Publication 3: Japanese Unexamined Patent Publication No. 2001-504727    Patent Publication 4: Japanese Unexamined Patent Publication No. H11-42250
For sanitary napkins to be worn by women during sleep, there have been known elongated sanitary napkins in which a buttocks-facing region is formed behind a vagina-facing region. However, menstrual blood trying to flow down the intergluteal cleft posteriorly during sleep cannot be effectively blocked only by applying the rear portion of the sanitary napkin to the buttocks.
The sanitary napkin of Patent Publication 1 has the primary absorbent member of a triangular cross-section, and the sanitary napkin disclosed in Patent Publication 2 has the tube of absorbent material. However, the primary absorbent member and the tube of absorbent material, which are both aimed to comfortably fit to the vaginal opening of women, are not intended to face the intergluteal cleft. Even if the primary absorbent member and the tube of absorbent material face the intergluteal cleft, since they are insufficient in stiffness to enter the intergluteal cleft, they cannot closely fit in the intergluteal cleft.
In the sanitary napkin disclosed in Patent Publication 3, on the other hand, the stiffening element prevents the hump from being easily crushed down. Although Patent Publication 3 discloses providing the raised portion at the rear end of the stiffening element for a fit into the intergluteal cleft, since the stiffening element is a stiff member such as a plastic sheet, the stiff member is liable to give an unpleasant feeling to the intergluteal cleft. In detail, the depth of the intergluteal cleft varies between the standing position and the supine position and the cleft becomes shallow in the lying position due to close contact between the opposing surfaces of the buttocks. When a wearer takes the supine position with the hump, which is reinforced by the stiff member, being positioned to face the intergluteal cleft, the stiff member hits the shallow cleft of the buttocks to easily give an unpleasant feeling, which leads to restlessness in sleep.
In the sanitary napkin disclosed in Patent Publication 4, the construction of the protrusion remains unclear, but this protrusion has a triangular cross-section and is not allowed to easily fit in the intergluteal cleft like those in Patent Publications 1 and 2.